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CVE-2025-48812: CWE-125: Out-of-bounds Read in Microsoft Office Online Server

Medium
VulnerabilityCVE-2025-48812cvecve-2025-48812cwe-125
Published: Tue Jul 08 2025 (07/08/2025, 16:57:19 UTC)
Source: CVE Database V5
Vendor/Project: Microsoft
Product: Office Online Server

Description

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

AI-Powered Analysis

AILast updated: 08/07/2025, 00:53:04 UTC

Technical Analysis

CVE-2025-48812 is a medium-severity vulnerability classified as an out-of-bounds read (CWE-125) affecting Microsoft Office Online Server version 1.0.0, specifically within the Microsoft Office Excel component. This vulnerability allows an unauthorized attacker to perform an out-of-bounds read operation, which can lead to local information disclosure. The flaw arises when the software improperly handles memory bounds during processing of Excel files, enabling an attacker to read memory locations beyond the intended buffer. Exploitation requires local access (AV:L) with low attack complexity (AC:L), no privileges (PR:N), but user interaction is necessary (UI:R). The vulnerability impacts confidentiality (C:H) but does not affect integrity or availability. The scope is unchanged (S:U), meaning the vulnerability affects only the vulnerable component without impacting other system components. No known exploits are currently in the wild, and no patches have been publicly released as of the publication date (July 8, 2025). The vulnerability was reserved in late May 2025 and published shortly thereafter. Given the nature of Office Online Server as a web-based platform for hosting and rendering Office documents, this vulnerability could be triggered when a user opens or interacts with a maliciously crafted Excel file through the online server interface, potentially leaking sensitive memory contents to the attacker locally. The requirement for local access and user interaction limits remote exploitation but does not eliminate risk in environments where users have access to the server or where malicious files are processed. The vulnerability's medium CVSS score of 5.5 reflects this balance of impact and exploitability.

Potential Impact

For European organizations, the primary impact of CVE-2025-48812 lies in the potential local disclosure of sensitive information from memory when processing Excel files via Microsoft Office Online Server. Organizations relying on Office Online Server to provide collaborative document editing and viewing services could face risks of data leakage if attackers gain local access or trick users into opening malicious Excel files. This could lead to exposure of confidential business data, intellectual property, or personally identifiable information (PII), undermining compliance with strict European data protection regulations such as GDPR. While the vulnerability does not allow remote code execution or denial of service, the confidentiality breach could facilitate further attacks or insider threats. The requirement for user interaction and local access reduces the likelihood of widespread exploitation but does not eliminate risk in multi-tenant environments, shared hosting, or where attackers have compromised user accounts. Additionally, organizations with high-value targets or sensitive data processed through Office Online Server should consider this vulnerability a significant concern. The absence of known exploits in the wild provides a window for proactive mitigation before active attacks emerge.

Mitigation Recommendations

1. Apply patches promptly once Microsoft releases an official fix for CVE-2025-48812. Monitor Microsoft security advisories closely. 2. Restrict local access to Office Online Server systems to trusted administrators only, minimizing the attack surface for local exploitation. 3. Implement strict file upload and content validation policies to prevent malicious Excel files from being processed by the server. 4. Employ application whitelisting and endpoint protection on servers hosting Office Online Server to detect and prevent suspicious activities. 5. Educate users about the risks of opening untrusted Excel files, especially in environments where Office Online Server is accessible. 6. Use network segmentation to isolate Office Online Server from critical systems and sensitive data repositories. 7. Monitor logs and system behavior for unusual access patterns or memory-related errors that could indicate exploitation attempts. 8. Consider disabling or limiting Office Online Server features that process Excel files if not essential, reducing exposure. These measures go beyond generic advice by focusing on access control, file validation, user awareness, and proactive monitoring tailored to the specific vulnerability context.

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Technical Details

Data Version
5.1
Assigner Short Name
microsoft
Date Reserved
2025-05-26T17:09:49.056Z
Cvss Version
3.1
State
PUBLISHED

Threat ID: 686d50d46f40f0eb72f91b83

Added to database: 7/8/2025, 5:09:40 PM

Last enriched: 8/7/2025, 12:53:04 AM

Last updated: 8/18/2025, 6:02:51 PM

Views: 9

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